Method and apparatus for molding non-pneumatic wheels

ABSTRACT

A method and apparatus for molding non-pneumatic wheels is provided. The exemplary method and apparatus allow for the use of the same molding system to manufacture wheels with different hub constructions. Different configurations of removable mold elements are utilized within the same molding system to provide wheels with different hub constructions.

PRIORITY STATEMENT

The present application claims priority to PCT/US14/070784, filed Dec.17, 2014 in the United States Receiving Office.

FIELD OF THE INVENTION

The subject matter of the present disclosure relates generally to amethod and apparatus for molding non-pneumatic wheels.

BACKGROUND OF THE INVENTION

Non-pneumatic wheel constructions and their benefits are described ine.g., U.S. Pat. Nos. 6,769,465; 6,994,134; 7,013,939; and 7,201,194.Some non-pneumatic tire constructions propose incorporating a shearband, embodiments of which are described in e.g., U.S. Pat. Nos.6,769,465 and 7,201,194, which are incorporated herein by reference.Such non-pneumatic tires provide advantages in tire performance withoutrelying upon a gas inflation pressure for support of the loads appliedto the tire.

In one example of a non-pneumatic wheel, a compliant band with a groundcontacting portion can be connected with a plurality of web elementsextending radially from a center element or hub. For certainconstructions, such non-pneumatic wheel may be formed by open castmolding in which a material such as e.g., polyurethane is poured into amold that forms all or part of the non-pneumatic tire. Reinforcements invarious parts of the non-pneumatic wheel may be molded in place. Forexample, one or more inextensible reinforcements such as cords may bemolded in place in the compliant band.

The molds used to cast such non-pneumatic wheel constructions are asubstantial part of the overall expense of manufacturing. Multiple,intricate features must be used to mold e.g., the individual webelements that extend between the hub and compliant band. Typically, themolds are carefully machined from metal having a high thermalconductivity such as e.g., aluminum.

The hub is used to connect the non-pneumatic wheel with a vehicle. Thehub may be connected directly to the vehicle or may be connected throughanother component such as a wheel center. A variety of differentconstructions or configurations may be used for the hub, which may beconstructed in whole or in part from one or more metals. Because of theassociated expense of creating the molds, a requirement of differentmolds for different hub configurations is undesirable.

Accordingly, a method and apparatus for molding non-pneumatic wheelswould be useful. More particularly, a method and apparatus that allowsuse of the same mold for manufacturing non-pneumatic wheels withdifferent hub configurations would be particularly beneficial.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for molding anon-pneumatic wheel. The exemplary method and apparatus allow for theuse of the same molding system to manufacture wheels with different hubconstructions. More particularly, multiple configurations of removablemold elements are utilized within the same molding system to providewheels with different hub constructions. The present invention canprovide a savings in manufacturing cost by avoiding the requirement of adifferent mold for each hub configuration. Additional objects andadvantages of the invention will be set forth in part in the followingdescription, or may be apparent from the description, or may be learnedthrough practice of the invention.

In one exemplary embodiment, the present invention provides anadjustable molding system for a non-pneumatic wheel, the non-pneumaticwheel including a plurality of tension-transmitting web elementsextending between a load support band and a hub, the non-pneumatic wheeldefining axial, radial, and circumferential directions. The moldingsystem includes an upper mold portion having a plurality of upper webforming elements spaced apart around the circumferential direction. Alower mold portion has a plurality of lower web forming elements spacedapart around the circumferential direction and are configured to receivethe upper web forming elements when the molding system is in a closedposition to form the tension transmitting web elements during themolding process. The upper mold portion and lower mold portion form aninternal cavity when the molding system is in the closed position.

This exemplary molding system also includes a first configuration ofremovable mold elements for positioning within the internal cavity. Thefirst configuration includes an upper mold bowl configured to form asurface of the wheel and a lower mold bowl supporting the upper moldbowl and configured to form a surface of the wheel. The lower mold bowlis supported on the bushing when the first configuration is positionedwithin the internal cavity. A removable bushing is positionable onto thelower mold portion. The molding system also includes a secondconfiguration of removable mold elements for positioning within theinternal cavity. The second configuration includes a spacer ring and aremovable bushing positioned onto the lower mold portion. The spacerring is received onto the bushing when the second configuration ispositioned within the internal cavity. The first and secondconfigurations are interchangeable within the molding system.

In another exemplary aspect, the present invention provides a method ofmolding a non-pneumatic wheel using a molding system that includes anupper mold portion and a lower mold portion that can be selectivelyjoined to form an internal cavity. The exemplary steps includepositioning a removable bushing and a lower mold bowl onto the lowermold portion; placing a compliant, load supporting band onto the lowermold portion; inserting an upper mold bowl onto the lower mold bowl;closing an upper mold portion onto the lower mold portion; and heatingthe lower mold bowl, upper mold bowl, and load supporting band to apredetermined temperature. A molding material may be poured into themolding system to form the non-pneumatic wheel.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 illustrates a perspective view of an exemplary non-pneumaticwheel of the present invention.

FIG. 2 illustrates a cross-sectional view along a meridian plane of theexemplary wheel of FIG. 1.

FIG. 3 illustrates a cross-sectional view along a meridian plane ofanother exemplary wheel of the present invention.

FIG. 4 is a partial cross-sectional and exploded perspective view of anexemplary molding system as may be used to manufacture the non-pneumaticwheels of FIGS. 1, 2, and 3.

FIG. 5 is a partial cross-sectional and exploded side view of anexemplary molding system as may be used to manufacture the non-pneumaticwheels of FIGS. 1, 2, and 3.

FIG. 6 is a cross-sectional view of the exemplary molding system ofFIGS. 4 and 5 shown in a closed position with an exemplary firstconfiguration of removable mold elements as may be used to manufacturethe exemplary wheel of FIGS. 1 and 2.

FIG. 7 is a cross-sectional view of the exemplary molding system ofFIGS. 4 and 5 shown in a closed position with an exemplary secondconfiguration of removable mold elements as may be used to manufacturethe exemplary wheel of FIG. 3.

DETAILED DESCRIPTION

For purposes of describing the invention, reference now will be made indetail to embodiments of the invention, one or more examples of whichare illustrated in the drawings. Each example is provided by way ofexplanation of the invention, not limitation of the invention. In fact,it will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Forinstance, features illustrated or described as part of one embodiment,can be used with another embodiment to yield a still further embodiment.Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

As used herein, the following definitions apply:

“Meridian plane” is a plane within which lies the axis of rotation ofthe tire or wheel. FIGS. 2 and 3, for example, are cross-sections of anexemplary non-pneumatic wheel of the present invention taken along ameridian plane.

The “radial direction” or “R” is perpendicular to the axis of rotationof the tire or wheel.

The “axial direction” or “A” is parallel to the axis of rotation of thetire or wheel and perpendicular to the radial direction.

The “circumferential direction” follows the circumference of the tire orwheel and is denoted with “C”.

FIG. 1 provides a perspective view of an exemplary non-pneumatic wheel50 that can be manufactured using the present invention while FIG. 2provides a cross-sectional view of wheel 50 taken along a meridianplane. The present invention is not limited to the particular shape,size, or appearance of the wheels shown in the figures. As will beunderstood using the teachings disclosed herein, wheels of other shapes,sizes, and appearances may be used as well.

Non-pneumatic wheel 50 includes a central mounting disk 202 this isprovided with a series of apertures 54 through which threaded lugs orother fasteners may be inserted in order to mount wheel 50 onto avehicle. Other mounting configurations may be used as well.Non-pneumatic wheel 50 also includes a compliant, load supporting band56 positioned radially outward of a hub 52 and positioned concentricallywith hub 52. A tread 48 may be formed on, or provided as part of, loadsupporting band 56. For example, a tread band may be adhered to loadsupporting band 56.

A plurality of tension-transmitting web elements 62 extend along theradial direction R between hub 52 and load supporting band 56. Webelements 62 are adjacent to one another and spaced apart aboutcircumferential direction C of wheel 50. Web elements 62 may have othershapes and configurations from what is shown in FIG. 1. Load supportingband 56 supports loads transmitted to non-pneumatic wheel 50 whenmounted to a vehicle using mounting disk 202. The load is transmitted bytension through web elements 62 to compliant band 56.

By way of example, load supporting band 56 may include a shear bandhaving an inner reinforcing band, outer reinforcing band, and a shearlayer positioned therebetween. The shear layer may be constructed e.g.,of an elastomeric material such as e.g., natural and synthetic rubbers,polyurethanes, foamed rubbers and polyurethanes, segmented copolyesters,and block co-polymers of nylon. The reinforcing bands may includereinforcements constructed from e.g., essentially inextensible cordreinforcements embedded in an elastomeric coating. Such reinforcementsmay include e.g., any of several materials suitable for use as tire beltreinforcements in conventional tires such as monofilaments or cords ofsteel, aramid or other high modulus textiles. Other constructions andmaterials may be used as well.

For the exemplary embodiment of FIGS. 1 and 2, hub 52 is connected witha central mounting disk 202 embedded within an outer toroidal portion 58of hub 52 using an exemplary molding system as described herein. By wayof example, central mounting disk 202 may be constructed from a metalwhereas hub 52 may be constructed from a polymeric material into whichdisk 202 can be molded. The polymeric material in the presentembodiment, also referred to herein as the molding material, may be anysuitable polymeric material such as e.g., a natural or synthetic rubber,polyurethane, foamed rubber and foamed polyurethane, segmentedcopolyesters, and block co-polymers of nylon.

Mounting disk 202 may be provided with one or more features to assist insecuring disk 202 to outer toroidal portion 58 of hub 52. For example,disk 202 may include a lip or bend 226 extending circumferentially aboutdisk 202. Mounting disk 202 may also include openings 228 (FIG. 4)through which material may extend during the molding process. Otherfeatures may be used as well.

FIG. 3 provides a cross-sectional view of another exemplary embodimentof wheel 50 taken along a meridian plane where the same referencenumerals denote the same or similar features as used in the embodimentof FIGS. 1 and 2. For this exemplary embodiment, wheel 50 also includesa central mounting disk 302. However, mounting disk 302 is not embeddedwithin hub 304. Instead, mounting disk 302 is attached to hub 50 along aflange 314. By way of example, central mounting disk 302 and hub 304 maybe constructed of one or more metals and welded or cast together.

FIG. 4 provides a perspective view of an exemplary embodiment of anadjustable molding system 100 for a non-pneumatic wheel while FIG. 5provides a side view of the same system 100. Molding system 100 has afirst configuration FC of removable mold elements that may be used tomold the exemplary wheel 50 of FIGS. 1 and 2. Molding system 100 alsohas a second configuration SC of removable mold elements that may beused to mold the exemplary wheel 50 of FIG. 3. In addition, firstconfiguration FC and second configuration SC are interchangeable witheach other within molding system 100 as will be further described inorder to manufacture wheels with different hub configurations. In FIGS.4 and 5, first configuration FC and second configuration SC are eachshown in an exploded, non-sectional view to show their sequencingrelative to each other within molding system 100. Only oneconfiguration, FC or SC, is used at time during the molding of anon-pneumatic wheel.

Molding system 100 includes an upper mold portion 102 and a lower moldportion 106. In FIGS. 1 and 2, the upper mold portion 102 and part ofthe lower mold portion 106 are shown in sectional views to more clearlyreveal certain interior components. Along with the FC and SCconfigurations of interchangeable mold elements, upper and lower moldportions 102 and 106 can be used to make the exemplary embodiment FIGS.1 and 2 as well as the exemplary embodiment of FIG. 3, which allows fora substantial savings in production costs by e.g., the avoidanceindividual molds for each embodiment of the non-pneumatic wheels.

Upper mold portion 102 includes a plurality of upper web formingelements 104 spaced apart along circumferential direction C. Lower moldportion 106 includes a plurality of lower web forming elements 108 alsospaced apart along circumferential direction C. When molding system 100is in a closed position as depicted in the cross-sectional views ofFIGS. 6 and 7, web forming elements 104 and 106 can be used to moldtension transmitting elements 62 of either of the previously describedexemplary embodiments of non-pneumatic wheel 50. More particularly, inthe closed position, the lower web forming elements 108 interlock withthe upper web forming elements 104 to provide spaces therebetween forthe formation of the web-like, tension transmitting elements 62 duringthe molding process in which a molding material such as e.g.,polyurethane is poured into molding system 100. In other embodiments ofsystem 100, web forming element 104 and 108 may meet to each form only aportion (e.g., half) of the web elements 62. Other constructions may beused as well.

Referring to FIGS. 4, 5, and 6, the first configuration FC, used for theexemplary embodiment of FIGS. 1 and 2, includes an upper mold bowl 200having an upper mold bowl forming surface 214. During moldingoperations, surface 214 forms part of the inner surface 64 of outertoroidal portion 58. A lower mold bowl 204 supports the upper mold bowl200. Lower mold bowl 204 provides a lower mold bold forming surface 216that also forms part of the inner surface 60 of outer toroidal portion58 during molding operations.

Central mounting disk 202 is held in place between upper mold bowl 200and lower mold bowl 204 when molding system 100 is in a closed positionshown in FIG. 6. It should be understood that central mounting disk 202is part of non-pneumatic wheel 50 and is not part of first configurationFC of removable mold elements. Central mounting disk 202 is positionedto be embedded within hub 52 when molding material is poured intomolding system 100 and fills the internal chamber or cavity 112 formedby mold portions 102 and 106 when molding system 100 is in the closedposition.

First configuration FC also includes a bushing 206 configured forreceipt of lower mold bowl 204 and upper mold bowl 200. Moreparticularly, when molding system 100 is in a closed position with firstconfiguration FC positioned in internal cavity 112 as shown in FIG. 6,bushing 206 projects along vertical direction V into an opening 220 inlower mold bowl 204, through opening 218 in central mounting disk 202,and into an opening 222 in upper mold bowl 200.

A central opening 232 of bushing 206 is used to position bushing 206onto a pilot 124 extending from lower mold portion 106. Bushing 206 hasa top end 208 and a bottom end 212. An annular rib 210 is formed onbottom end 212 and extends along circumferential direction C. Rib 210supports lower mold bowl 205 on pilot 124. As shown in FIG. 6, rib 210is received into a recess 224 formed in the interior 230 of lower moldbowl 205. During molding operations as described below, bushing 206 canbe used to lift lower mold bowl 204, mounting disk 202, and upper moldbowl 200 simultaneously to remove from, or place the same into, moldingsystem 100. For example, a robotic arm can be used to grasp bushing 206by top end 208 and position as needed.

Additionally, when in the closed position as shown in FIG. 6, loadsupport band 56 is positioned between upper mold portion 102 and lowermold portion 106. Further, in the closed position, upper mold bowl 200and lower mold bowl 204 are positioned concentrically within loadsupport band 56. Similarly, upper web forming elements 204 and lower webforming elements 108 are positioned within load support band 56 whenmolding system 100 is in the closed position. As such, during moldingoperations, load support band 56 forms part of the mold when moldingmaterial is poured into the internal cavity 112 formed by the closing ofmolding apparatus 100. This allows the molding material to join withload support band 56 to form non-pneumatic wheel 50.

An exemplary method of using molding system 100 to manufacture exemplarynon-pneumatic wheel depicted in FIGS. 1 and 2 will now be described.Using the teachings disclosed herein, it will be understood that othermethods with different steps or a different sequence of steps may beused in still other exemplary methods of the present invention.

In one exemplary method, the molding surfaces of molding system 100 arecleaned. After a preheating step, the molding surfaces are treated witha coating to help release molding material after molding and curing.Bushing 206 can be used to lift lower mold bowl 204, mounting disk 202,and upper mold bowl 200 simultaneously and place onto the lower moldportion 106 of molding system 100. Load support band 56 is placed withina complementary groove 118 defined by lower mold portion 106. The uppermold portion 102 is then placed onto lower mold portion 106 with supportband 56 received into complementary groove 122.

The molding system 100 is heated again until e.g., a predeterminedtemperature is reached. Next, a molding material such as e.g.,polyurethane or another material as previously described is poured intomolding system 100. More specifically, the molding material is pouredthrough e.g., opening 120 and allowed to fill internal cavity 112 formedby the closed position of molding system 100. The mold material fillsthe interstitial spaces formed by the upper and lower mold portions 102and 106 to form wheel 50. During the pouring step, after the pouringstep, or at the same time as the pouring step, molding assembly 100 isrotated to e.g., help distribute the molding material within moldingsystem 100 and remove bubbles that may be entrained in the moldingmaterial.

Molding system 100 is then placed into an oven for additional heating soas to cure the molding material. Once the molding material is cured,molding system 100 can be removed from the oven. Upper mold portion 102can then be removed and non-pneumatic wheel 50 can be de-molded. Bushing206 can be used to remove the cast wheel 50 along with the removablemold elements from lower mold portion 106.

Referring to FIGS. 4, 5, and 7, the second configuration SC can be usedto mold the exemplary wheel of FIG. 3 and is interchangeable with firstconfiguration FC. Second configuration SC includes a spacer ring 306 andbushing 206. When mold system 100 is in the closed position shown inFIG. 7, mounting disk 302 rests upon spacer ring 306. Spacer ring 206defines an opening 310 through which bushing 206 projects along verticaldirection V. Pilot 124 projects along vertical direction V throughopening 232 in bushing 206.

Mounting disk 302 is located within hub 304. Hub 304 is supported uponlower mold portion 106. When molding system 100 is in the closedposition shown in FIG. 7, a spring loaded pour cap (not shown) pushesdown onto the top edge 300 of canned hub 304 to seat the hub onto thelower mold portion 106.

Additionally, when in the closed position shown in FIG. 7, load supportband 56 is positioned between upper mold portion 102 and lower moldportion 106. Specifically, load support band 56 is received intocomplementary grooves 118 and 122. Further, in the closed position, cap300 and hub 304 are positioned concentrically within load support band56. Similarly, upper web forming elements 204 and lower web formingelements 108 are positioned within load support band 56 when moldingsystem 100 is in the closed position. As such, during moldingoperations, the outer surface 308 of hub 304 and the inner surface ofload support band 304 forms part of the mold when molding material ispoured into the internal cavity 112 formed by the closing of moldingapparatus 100. This allows the molding material to join with theexternal surface 308 of hub 304 and load support band 56 to formnon-pneumatic wheel 50. Hub 304 and mounting disk 302 form part of wheel50 and are not part of the second configuration SC of removable moldelements.

As will be understood using the teachings disclosed herein, methodssimilar to that previously described for first configuration FC may beused to mold the exemplary wheel 50 of FIG. 3 using the secondconfiguration SC. As previously stated, configurations FC and SC areinterchangeable. Either configuration may be removed from molding system100 to allow for installation of the other configuration depending uponthe wheel hub configuration that will be manufactured.

Multiple bushings 206 may be used with the present invention. Forexample, different configurations of wheels 50 may use bushings 206 ofdifferent sizes and shapes. In addition, to facilitate manufacture,multiple bushings 206 may be used. For example, during manufacture,several bushings 206 may be used at the same time so that as mold system100 is unloaded with a molded wheel 50, another assembly of e.g.,bushing 206, bowls 200 and 204, along with disk 202 may be loaded intomold assembly 100 in preparation for molding another wheel 50. Othermethods may be used as well.

While the present subject matter has been described in detail withrespect to specific exemplary embodiments and methods thereof, it willbe appreciated that those skilled in the art, upon attaining anunderstanding of the foregoing may readily produce alterations to,variations of, and equivalents to such embodiments. Accordingly, thescope of the present disclosure is by way of example rather than by wayof limitation, and the subject disclosure does not preclude inclusion ofsuch modifications, variations and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the artusing the teachings disclosed herein.

What is claimed is:
 1. An adjustable molding system for a non-pneumatic wheel, the non-pneumatic wheel including a plurality of tension-transmitting web elements extending between a load support band and a hub, the non-pneumatic wheel defining axial, radial, and circumferential directions, the molding system comprising: an upper mold portion having a plurality of upper web forming elements spaced apart around the circumferential direction; a lower mold portion having a plurality of lower web forming elements spaced apart around the circumferential direction and configured to receive the upper web forming elements when the molding system is in a closed position to form the tension transmitting web elements during a molding process, wherein the upper mold portion and lower mold portion form an internal cavity when the molding system is in the closed position; a first configuration of removable mold elements for positioning within the internal cavity, the first configuration comprising a removable bushing positioned onto the lower mold portion; an upper mold bowl configured to form a surface of the wheel; a lower mold bowl supporting the upper mold bowl and configured to form a surface of the wheel, wherein the lower mold bowl is supported on the bushing when the first configuration is positioned within the internal cavity; a second configuration of removable mold elements for positioning within the internal cavity, the second configuration comprising a spacer ring; and a removable bushing positioned onto the lower mold portion and onto which the spacer ring is received when the second configuration is positioned within the internal cavity; wherein the first and second configurations are interchangeable within the molding system.
 2. The adjustable molding system of claim 1, wherein the bushing extends vertically into an opening in the lower mold bowl and into an opening in the upper mold bowl.
 3. The adjustable molding system of claim 2, wherein the bushing includes top end and a bottom end, the bottom end defining an annular rib onto which the lower mold bowl is received.
 4. The adjustable molding system of claim 2, wherein the lower mold bowl defines an annular recess into which the annular rib is received.
 5. The adjustable molding system of claim 2, further comprising a pilot extending from the lower mold portion, wherein the lower mold bowl is removably received onto the pilot.
 6. The adjustable molding system of claim 1, further comprising a mounting disk positioned between the upper mold bowl and the lower mold bowl when the molding system is in the closed position with the first configuration in the internal cavity.
 7. The adjustable molding system of claim 1, wherein the load support band is positioned between the upper mold portion and the lower mold portion when the molding system is in the closed position with the first configuration in the internal cavity.
 8. The adjustable molding system of claim 7, wherein the upper mold bowl and the lower mold bowl are positioned concentrically within the load support band when the molding system is in the closed position.
 9. The adjustable molding system of claim 8, wherein the upper and lower web forming elements are positioned within the load support band when the molding system is in lathe closed position. 